Pigment compositions

Abstract

New pigment compositions, in storage-stable free-flowing flake form comprise (a) pigment; and (b) water in a maximum amount of 10% by weight above the critical moisture content of the pigment component. The pigment compositions are produced by partially de-watering conventional aqueous pigment compositions, especially aqueous pigment filter-cakes.

I claim: 
     
       1. Method of producing a free flowing, storage-stable pigment composition consisting essentially of a pigment in flake from containing water in a maximum amount of 10% by weight above the pigment's critical moisture content comprising de-watering a conventional pigment press-cake containing 60-80% by weight of water, in a press comprising two counter-rotating endless bands moving under tension around one or more rollers which applies surface pressure to said filter-cake; subsequently causing said filter-cake to be subjected to variable line pressure of 50 N/mm to 250 N/mm between one or more pairs of rollers to which a variable pressure is applied; the conditions of surface pressure, line pressure and band speed being so chosen that the final water content of the pigment composition is no more than 10% by weight above the critical moisture content of the pigment, and removing the de-watered pigment from the press in a manner to provide the composition in flake form.